HP9100B
vintage-technology
oooh no, I am very sorry to ask this (I get at least a couple of dozen
requests a month for "how much is my calculator worth"), but as I do
not ever buy HP calculators I could do with some help.
Yet to be examined and put on my website.
So rough guesses please for TWO HP9100B calcs from 1968, with printer
add-ons, working, two plotters, a couple of boxes of cards and an
extended memory unit. I have seen one comment saying $1800 just for
the calculator unit. Is this true?
If you are not familiar with this it is all-transitor programmable
with card reader, CRT display, magnetic core memory, and I can only
just lift it up.
Again, sorry for asking, but just not my brand.
Regards
Adam Jones
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Adam Jones
Windham, ME
vintage-technology
collectors. It certainly is a thing of beauty! So completely over-
engineered. Can't wait to start examining the bits in greater detail.
And to think, I have just spent most of my night dissecting a Casio
F-2 for my site.
Cheers!
>
> - Show quoted text -
Rick Bensene
Congratulations on a finding a treasure chest of HP calculator jewels!
These machines are among the most desirable (with the 9100A being a
bit more desirable, since it was HP's first) HP calculators, and among
the top in overall desirability for early desktop calculator
technology. The fact that these machines are all-transistor (with
only some analog ICs in the mag-card reader circuitry) is truly
stunning for their size and amazing capabilities. These were truly
masterpieces of electronic (as well as mechanical and aesthetic)
design.
The 9100B calculators are indeed worth in the ballpark mentioned, if
not more, with the main variable being whether they are fully
functional. The market right now is a bit soft because of the
economy, but typically the folks that want these kinds of machines
have pockets deep enough to be willing to pay well for them. Issues
that can affect operation are the mag-card readers can have problems
with the rubber rollers that guide the card into and out of the
machine getting mushy/sticky. The core memory system can have issues
with component drift that can cause malfunctions, but most of the
time, there are adjustments that were designed-in to compensate for
this, though tuning the adjustments can be really tedious. (Tony
Duell, a big HP calculator fan and master of reverse engineering, has
developed his own schematics for the 9100B based on him tearing a
machine completely apart and reverse engineering it!) The analog
circuitry for the display generation can also drift out of spec,
resulting in malformed display on the CRT, but again, adjustments can
typically compensate for this. If the CRT is bad, that's really bad,
as these are basically unobtainium today. If you ship the machines,
they must be packed very carefully to avoid shocking the CRT. As with
any old electronics, capacitors in the power supply can suffer
malformation, which can result in malfunction. Fortunately, HP used
very high quality computer-grade filter capacitors in the power
supply, so there's less chance of this on their machines than other
manufacturers.
The printer option is pretty uncommon to find in working condition.
Its great that you got them with the machines. They have problems
with the paper roller turning to goo, which is difficult to repair.
It is also difficult to find the electro-sensitive paper that this
printer used, so hopefully you got some paper with the printers. The
stylus that transfers the electrical charge to mark the paper can also
get damaged pretty easily, and if that happens, no replacements are
available as far as I know.
The plotters are quite unusual, and definitely a great peripheral.
The manual for the plotter is important, as programming them is
definitely non-intuitive. The plotters are unusual in that they use
analog servos rather than stepper motors. Since the plotter is
really analog, component drift can cause issues, but again, HP's
superb engineering designed-in adjustments to compensate for this, so
many times, they can be brought back to functionality by a good
electronics tech who knows analog electronics. Unfortunately, finding
pens for these plotters today is difficult. Any originals are
generally long-since dried out. Adaptations can be made to use other
pens. Without an appropriate pen, it's hard to do much with the
plotter, though.
The mag cards come up from time to time on places like eBay. They
have the most value for collectors if they are unmarked, and have
unmarked sleeves. Cards with the corner cut off (write protect) are
worth significantly less. If you have the neat plastic case for the
cards, that's a bonus.
Lastly, the memory expansion unit is very rare. It uses core memory
just like the calculator, though ICs are used in the circuitry of this
device. The critical thing is having the cables that connect the
memory expansion unit to the calculator. These units can suffer the
same amplifier drift issues as the calculator, and adjusting the
constant current source for the drivers, as well as the read
amplifiers can be tedious, but more often than not, malfunctions can
be addressed by adjusting variable components built into the design.
However, schematics aren't available (at least so far as I am aware),
so troubleshooting is difficult. HP wasn't big on publishing
schematics...instead, they published module-based troubleshooting and
service information.
In order to connect all of the peripherals, you'll need a buffer box,
as the calculator can only support one peripheral option connected it
to it at a time (the printer connects to its own port, so the printer
can always be used). The buffer box splits out the port on the
calculator to additional ports so that you could, for example, connect
the plotter and the memory expansion at the same time. The buffer box
units are quite uncommon.
Generally, I refrain from providing valuations, but in this case, I'll
make an exception. These values are based on long-time observation of
the market, and of course, are subjective since I can't actually see
the equipment involved in terms of condition, operability, and
availability of accessories. They reflect what I believe to be
reasonable values based on today's (somewhat depressed) market. The
price is for the device only with its power cord and necesasry
connecting cables. Some additional value can be gleaned if original
documentation, literature, dust covers, and other accessories are
available and in good condition.
The peripheral devices are really only of use to someone that has a
9100-series calculator, thus their general market appeal is somewhat
limited as compared to the calculators themselves. However, to
someone who has a 9100 that would like to add periperhals, these are
definitely desirable and can be quite valuable. I'd guesstimate that
the printers (if working and have some supply of paper) are probably
worth in the $400 to $800 range each depending on condition and
operability. The plotters are probably worth somewhere around the
same amount, perhaps a little more due to rarity, if in operating
condition and in good cosmetic condition. The memory expansion unit
is probably worth somewhere around $1250 to $1500, perhaps more, if
fully operational, and in good condition.
The value of the mag cards can vary depending on whether they are NOS
or used, and if the case is available.
Manuals are available for all of this stuff on the MoHPC DVD, but
having the original manuals adds value. You didn't mention if you got
manuals with the equipment. Things like original dust covers, power
cords, original paperwork (warranty cards, sales receipt) also add
value, and of course, if the original boxes are available for the
stuff in good condition, that too adds value to the collector types.
I hope this is helpful.
Rick Bensene
The Old Calculator Museum
http://oldcalculatormuseum.com
vintage-technology
thanks for that long answer. So two of them is even rarer then!
Not worried if the printer is not working as I have a garage-full of
printer spares.
Now I am really looking forward to creating a huge page on my web
site,
That will take me a few months I am sure.
Best regards
Emil
vintage-technology
this must be customised to the unit sold
regards
dramsey
I just obtained two 9100Bs, one with the printer. The printer works
perfectly but the very bottom wire on the printhead has failed; a
continuity check reveals that there's no connection between the end of
the flex cable where it's clamped to the printer board and the last
wire in the printhead. I suspect the problem lies inside the black
plastic block the print wires are clamped in; there's a small amount
of greenish corrosion visible there. I'm tempted to take the printhead
apart but am afraid that doing so would yield a tiny shower of
disintegrating flex cable bits that would render the printer
completely useless.
Do you have any printhead assemblies or complete printers you'd be
willing to sell? I'd really like to get this one working.
Thanks,
-- David Ramsey
On Oct 22, 12:39 pm, vintage-technology <emil.du...@btopenworld.com>
wrote: